If a little knowledge was a dangerous thing, a lot was lethal.

A little knowledge is a dangerous thing, but a little want of knowledge is also a dangerous thing.

They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance.

A little learning is a dangerous thing; Drink deep, or taste not the Pierian spring.

True, a little learning is a dangerous thing, but it still beats total ignorance.

Don't play for safety - it's the most dangerous thing in the world.